It is known that rotors for steam and gas turbines, for compressors, and for turbogenerators are constructed of individual rotational bodies with hollow spaces. DE 26 33 829 C2 describes, e.g., rotors constructed of forged parts in the shape of disks or hollow cylinders, whereby the individual disks or drums (hollow cylinders) preferably have a constant thickness in the rotor center. The disks or drums are hereby connected with each other via low-volume welding seams.
In order to keep, e.g., the operating temperatures of gas turbine rotors during full load operation approximately constant, they must be cooled. For this purpose, cooling air is usually supplied into the rotor through the waste gas side shaft end. The rotor therefore has a center bore which extends from the waste gas side shaft end to the last turbine disk. This bore forms the rotor cooling air channel. The cooling air is removed from a specific compressor stage and is supplied via a special conduit into the central bore at the waste gas side end of the rotor, whereby the conduit/rotor transition is sealed with labyrinth seals. The cooling air flows through the rotor cooling air duct and then into the hollow space between the two turbine disks before it passes the turbine blades or reaches the rotor surface through radial hollow spaces and mixes with the waste gas stream.
This known arrangement does permit a cooling of the rotor once full operation is reached, so that small blade clearances and high degrees of efficiency can be achieved. But a positive influencing of the rotor under transient operating conditions, which are particularly critical due to the different thermal behavior of rotor and stator, is not possible.
EP 0 761 929 A1 describes a rotor for thermal turbomachines which substantially eliminates these disadvantages. In this rotor, in particular in a compressor part, center part, and turbine part arranged on a shaft, whereby the rotor consists primarily of individual rotational bodies that are welded to each other. This geometric shape results in the creation of axially symmetrical hollow spaces between the respectively adjoining rotational bodies. Another cylindrical hollow space is provided that extends around the center axis of the rotor and reaches from the down-stream end of the rotor to the last hollow space up-stream. At least two pipes of varying diameters and lengths which overlap at least partially and are placed in the cylinder-shaped hollow space, whereby each of the pipes is firmly anchored at least at one fixed point, and the fixed points of the pipes are located at different places. The pipes are each provided with at least two through-openings in the mantle, whereby at least one opening in the turbine part and at least one opening in the compressor or center part, and the openings of the various pipes in the warm operating state overlap in the turbine part, while in the cold state they overlap in the compressor and middle part. This rotor can be thermally regulated by an air supply.
The disadvantage of this solution known from EP 0 761 929 A1 is that a relatively large amount of air is required for the thermal regulation of the rotor since the heat transmission coefficient is low. There is an additional expenditure to provide this air.